Acoustic wave device

Abstract

An acoustic wave device includes a support substrate including a main surface including first and second regions adjacent to each other in a plan view; a multilayer body including an intermediate layer in the first region of the support substrate and a piezoelectric layer on the intermediate layer, and including a side surface; an IDT electrode on the piezoelectric layer of the multilayer body; and an insulating film in the second region of the support substrate to cover the side surface of the multilayer body. An angle defined between the main surface of the support substrate and the side surface of the multilayer body is a tilt angle, and the side surface of the multilayer body includes portions having different tilt angles at a portion covered with the insulating film.

What is claimed is: 
     
       1. An acoustic wave device comprising:
 a support substrate including a main surface including a first region and a second region adjacent to the first region in a plan view; 
 a multilayer body including an intermediate layer in the first region of the support substrate and a piezoelectric layer on the intermediate layer, and including a side surface; 
 an IDT electrode on the piezoelectric layer of the multilayer body; and 
 
       an insulating film in the second region of the support substrate and covering the side surface of the multilayer body; wherein
 an angle defined between the main surface of the support substrate and the side surface of the multilayer body is a tilt angle, and the side surface of the multilayer body includes portions having different tilt angles at a portion covered with the insulating film. 
 
     
     
       2. The acoustic wave device according to  claim 1 , wherein
 the piezoelectric layer and the intermediate layer each include a side surface; and 
 a tilt angle of the side surface of the piezoelectric layer is smaller than a tilt angle of the side surface of a layer adjacent to the piezoelectric layer in the intermediate layer. 
 
     
     
       3. The acoustic wave device according to  claim 1 , wherein
 the intermediate layer includes a plurality of layers each including a side surface; and 
 a tilt angle of the side surface of at least one layer among the plurality of layers is different from a tilt angle of the side surface of another layer. 
 
     
     
       4. The acoustic wave device according to  claim 1 , wherein
 the support substrate is a high acoustic velocity support substrate; 
 the intermediate layer is a low acoustic velocity film provided on the high acoustic velocity support substrate; 
 an acoustic velocity of a bulk wave propagating through the high acoustic velocity support substrate is higher than an acoustic velocity of an acoustic wave propagating through the piezoelectric layer; and 
 an acoustic velocity of a bulk wave propagating through the low acoustic velocity film is lower than an acoustic velocity of a bulk wave propagating through the piezoelectric layer. 
 
     
     
       5. The acoustic wave device according to  claim 1 , wherein
 the intermediate layer includes a high acoustic velocity film provided on the support substrate, and a low acoustic velocity film provided on the high acoustic velocity film; 
 an acoustic velocity of a bulk wave propagating through the high acoustic velocity film is higher than an acoustic velocity of an acoustic wave propagating through the piezoelectric layer; and 
 an acoustic velocity of a bulk wave propagating through the low acoustic velocity film is lower than an acoustic velocity of a bulk wave propagating through the piezoelectric layer. 
 
     
     
       6. The acoustic wave device according to  claim 1 , wherein
 the intermediate layer is an acoustic reflection film provided on the support substrate; and 
 the acoustic reflection film includes a high acoustic impedance layer relatively high in acoustic impedance and a low acoustic impedance layer relatively low in acoustic impedance, and the high acoustic impedance layer and the low acoustic impedance layer are alternately laminated. 
 
     
     
       7. The acoustic wave device according to  claim 3 , wherein
 the intermediate layer includes a plurality of metal layers and an insulating layer provided between the plurality of metal layers, and the plurality of metal layers and the insulating layer each include a side surface; and 
 a connection electrode which electrically connects the plurality of metal layers to each other is provided on the side surface of the insulating layer. 
 
     
     
       8. The acoustic wave device according to  claim 1 , wherein a metal film which extends from a top of the piezoelectric layer to a top of the insulating film is provided. 
     
     
       9. The acoustic wave device according to  claim 1 , wherein the piezoelectric layer includes a first main surface and a second main surface facing each other, the IDT electrode is provided on the first main surface, and the insulating film extends onto the first main surface. 
     
     
       10. The acoustic wave device according to  claim 1 , wherein
 the main surface of the support substrate includes a plurality of the first regions; 
 the multilayer body is provided in each of the plurality of first regions of the support substrate, and the IDT electrode is provided on the piezoelectric layer of each of the multilayer bodies; and 
 the side surface of each of the multilayer bodies is covered with the insulating film. 
 
     
     
       11. The acoustic wave device according to  claim 1 , wherein the insulating film is a photosensitive polyimide film. 
     
     
       12. The acoustic wave device according to  claim 1 , wherein, in the plan view, the insulating film is in contact with an entire or substantially an entire circumference of the side surface of the multilayer body. 
     
     
       13. The acoustic wave device according to  claim 8 , wherein the metal film is a wiring electrode that is electrically connected to the IDT electrode. 
     
     
       14. The acoustic wave device according to  claim 1 , wherein, in the plan view, a boundary between the multilayer body and the insulating film is covered with a metal film. 
     
     
       15. The acoustic wave device according to  claim 1 , wherein the tilt angle of the side surface of each layer of the multilayer body is less than about 90°. 
     
     
       16. The acoustic wave device according to  claim 4 , wherein
 the high acoustic velocity support substrate is a silicon substrate; and 
 the low acoustic velocity film is a silicon oxide film. 
 
     
     
       17. The acoustic wave device according to  claim 1 , wherein the intermediate layer includes only a single film layer.